A quantum dot enhancement film (QDEF) is an optical element currently used in backlight modules to enhance color display. Generally, a conventional quantum dot enhancement film may include two types of quantum dots dispersed in a thin film. When a light source irradiates light of a certain wavelength range, e.g., blue light, on the conventional quantum dot enhancement film, the two types of quantum dots may correspondingly emit red light and green light upon receiving the blue light, resulting in white light emission due to mixing of the same. An output ratio of the produced red and green lights to the incident blue light may be altered so that color adjustment of the mixed white light into a relatively natural light color is possible. By doing so, the color display on a display device utilizing the conventional quantum dot enhancement film can be relatively accurate.
Referring to FIGS. 1 and 2, a conventional display device includes a backlight module 1, a plurality of optical films 17 and a liquid crystal display panel (not shown). The backlight module 1 comprises a back plate 11, a side frame member 12 that is connected to the back plate 11 and that cooperates with the back plate 11 to define a receiving space 10, a light guide plate 13 that is disposed in the receiving space 10, a quantum dot enhancement film 14 that is disposed on a bottom surface of the light guide plate 13 and that is located in the receiving space 10, a light source (not shown) that is disposed in the receiving space 10 and adjacent to the light guide plate 13, and a reflector 15 that is disposed to surround the light guide plate 13. The optical films 17 are stacked on the light guide plate 13 opposite to the quantum dot enhancement film 14, and the liquid crystal display panel is provided thereupon. The light emitted from the light source of the backlight module 1 may be transmitted into and propagate within the light guide plate 13, where the optical films 17 can promote light reflection at a top surface of the light guide plate 13. Consequently, the total amount of light incident into the quantum dot enhancement film 14, as illustrated in FIG. 2, may be increased, generating a compensation light therefrom (such as red and green lights for the incident blue light). However, lateral portions of the quantum dot enhancement film 14 may have an insufficient amount of light incident from the light guide plate 13. Due to the lack of compensation light, the color of light emitted from lateral portions of the conventional display device may differ from that of the light emitted from central portions, resulting in an undesirable, so-called “blue edge” phenomenon to occur on the conventional display device.